Karyotype, DNA Content and Meiotic Behaviour in Five South American Species ofVicia(Fabaceae)

This paper presents the karyotype, DNA content and meiotic behaviourof five species ofViciafrom Argentina (V. macrogramineaBurk.,V.gramineaSM.,V. epetiolarisBurk.,V. pampicolaBurk. andV. nanaVog.).All the species have the same chromosome number and karyotypeformula (2n=14; 6m+4st+4t). Each species, however, displaysa characteristic number and position of the nucleolar organizerregion (NOR) and different sizes of the respective satellites,confirmed by Ag-NOR banding. Moreover, significant differenceswere found in the total chromosome volume (TCV) and DNA contentof the species. Positive correlations between DNA content andTCV, and between DNA content and type of life cycle were alsofound. TCV and DNA content are lower inV. nana(annual) and higherinV. macrograminea(biennial–perennial). The material displayedmarked karyotypic orthoselection, with similar karyotypes inall studied species, even when the overall chromosome size varied.Evolutionary changes in DNA amount are proportional to the relativelength of each chromosome arm, maintaining karyotypic uniformity.Significant differences were found between the meiotic behaviourofV. gramineaand that of the other species.V. gramineahas alower frequency of ring bivalents and chiasmata per cell, andalso has a lower interstitial chiasma frequency. In general,the results are congruent with the morphological data reportedfor these species.Copyright 1998 Annals of Botany Company. Viciaspecies, karyotype, orthoselection, nuclear DNA content, NOR banding, meiotic behaviour.     

Pulsed pheromone stimuli affect the temporal response of antennal receptor neurones of the adult cabbage looper moth

Abstract. Male cabbage looper moths, Trichoplusia ni (Hiibner) (Lepidoptera: Noctuidae), fly upwind in response to pheromone blends produced and released by calling conspecific females. Specialized sensilla on the male antenna contain sensitive, highly specific olfactory receptor neurones which respond to constant olfactory signals, with a phasic-tonic pattern of action potential discharge. Olfactory stimuli in nature are not uniform. They are thought to consist of pulses of odours whose distribution is shaped by wind and local environmental features. We begin to evaluate this natural situation by stimulating pheromone-sensitive sensilla with short (200 ms) paired pulses of the major component of the female's pheromone blend, (Z)-7-dodecen-l-ol acetate (Z-7,12:AC). Different stimulus protocols in which the pulses were separated from each other by varying intervals were evaluated. The interval between pulses had a large effect on the phasic component of the response. Intervals between pulses as short as 30 ms reduced the response to a second pulse by > 50%. When the intervals between pulses were longer than 3 s, significant differences were not seen between the responses to the first and second pulse. Implications for male orientation in natural, female-produced, pheromone plumes are discussed.     

Different seasonal rearing conditions do not affect pheromone-sensitive receptor neurons of the adult cabbage looper moth, Trichoplusia ni

Abstract. In southern parts of the United States the cabbage looper moth, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), is multivoltine, and therefore successive generations experience different environmental conditions during development from larvae to adults.Since environmental conditions are thought to influence pheromone communication, we tested the effects of two different temperature and light regimes (selected to mimic those occurring in the spring and summer growing seasons in the south) during rearing on the response characteristics of the adult male olfactory receptor neurons responsible for detecting the major component of the female pheromone.The dose-response functions of receptor neurons from the warm- and cold-reared insects were similar in both their slopes and thresholds to stimulation with the major component of the female-emitted pheromone, (Z)-7, dodecen-1-ol acetate and (Z)-7, dodecen-1-ol, a behavioural inhibitor.In double pulse experiments, designed to emulate the temporal dispersion of pheromone in nature, neurons were stimulated with short pulses (200 ms) of (Z)-7, dodecen-1-ol acetate separated by varying intervals.Intervals as short as 30 ms reduced the response to a second pulse by over 50%.When the intervals between pulses were longer than 2 s, significant differences were not seen between the responses to the first and to the second pulse.These temporal response patterns were similar in both warm- and cold-reared animals.     

Use of Alternative Plant Resources by Common Marmosets (Callithrix jacchus) in the Semi‐Arid Caatinga Scrub Forests of Northeastern Brazil

The common marmoset (Callithrix jacchus) is amply distributed in the Brazilian Northeast, but little is known of its ecology in the semi‐arid Caatinga scrublands. The present study provides the first detailed data on the composition of the diet of C. jacchus in Caatinga ecosystems, derived from observations at four sites in the state of Sergipe. While exudate sources were gouged at all four sites in a manner typical of the species, fruit was the principal component of the diet at the main study site during most months, and a number of unusual items were eaten, including leaves, and the reproductive parts of cacti and bromeliads. These plants are rarely recorded in marmoset diets, but are common in caatinga habitats. Leaves were ingested during 5 of the 8 months monitored at the main study site, reaching 39.74% of the diet in 1 month, and appeared to be an alternative fallback food to plant exudates during periods when fruit was scarce. Three species of cactus provided both flowers and fruits, while the terrestrial bromeliad, Encholirium spectabile, provided nectar (30.81% of the diet in November). Approximately half of the plant species (and three families) identified in this study had not been recorded previously in the diet of Callithrix. Overall, the data suggest that, while the marmosets exploit the same types of plant foods in the Caatinga, the resource base is quite distinct from that of the Atlantic Forest. Other differences, such as relatively small groups and large home ranges, may contribute to divergent ecological patterns, which require more systematic investigation. Am. J. Primatol. 75:333‐341, 2013. © 2012 Wiley Periodicals, Inc.     

Thyroid Hormone Receptors in the Developing Rat Brain

It is widely believed that the adult mammalian brain is insensitiveto thyroid hormones unlike the neonatal brain which is criticallydependent on these hormones for the development of normal structureand function. Recent studies have demonstrated the presenceof limited capacity, high affinity, triiodothyronine (T3) bindingnuclear sites in tissues that are considered responsive to thyroidhormones. Furthermore, there is evidence from studies on peripheraltissues that these T3 binding sites act as true receptors ininitiating thyroid hormone action. This report examines whetherthe higher sensitivity of neonatal brain to thyroid hormonesand the purported decline in sensitivity in adulthood are relatedto changes in the concentration and affinity characteristicsof thyroid hormone receptors in rat cerebral nuclei. Analysisof Scatchard plots of in vitro T3 binding data indicate thatcerebral nuclei from adult rats contain T3 specific nuclearbinding sites at a concentration comparable to that presentduring the period when the brain is critically dependent onthe presence of thyroid hormones and exceed that in the liver,a tissue generally considered thyroid sensitive. Neonatal thyroidectomysignificantly increased the number of binding sites. The resultsshow that the apparent unresponsiveness of the cerebral cortexof adult rats to thyroid hormones is not due to the absenceor a low density of T3 nuclear binding sites. The significanceof these results is discussed.     

Biodiversity and biogeography in Madagascar: revision of the endemic flea beetle genus Neodera Duvivier, 1891 with description of 19 new species (Coleoptera,Chrysomelidae, Galerucinae,Alticini)

A revision of the Malagasy flea beetle genus Neodera Duvivier 1891 is provided. This genus includes 31 species of which 19 are new to science: Neodera amplicollis sp.n. , N. breviantennata sp.n. , N. didiensis sp.n. , N. diversitarsis sp.n. , N. jenisi sp.n. , N. kraussi sp.n. , N. longicollis sp.n. , N. marojejyensis sp.n. , N. nigrotibialis sp.n. , N. opaca sp.n. , N. pauliani sp.n. , N. perroti sp.n. , N. peyrierasi sp.n. , N. reducta sp.n. , N. similvadoni sp.n. , N. sogai sp.n. , N. speronata sp.n. , N. straminoides sp.n. and N. vadoni sp.n. . The following two synonymies are proposed: N. fraterna Duvivier = N. amarella Bechyné and N. fulva Jacoby = N. hilari Bechyné. In addition, neotypes for N. emarginata Duvivier and N. fraterna Duvivier, and lectotypes for N. fulva Jacoby, N. imitatrix Duvivier, N. madagassa (Harold), N. picticornis (Harold), N. transversicollis Jacoby and N. varicornis (Harold) are designated. Additionally, the revision comprises a key for the identification of all 31 species considered, some habitus photos, microscope and scanning electron micrographs of many diagnostic characters, including median lobe of aedeagus and spermatheca. A first phylogenetic analysis based on parsimony is also provided. It is used with distributional data to put forward hypotheses about the natural history of the taxon in the light of the species differentiation models proposed thus far for Madagascar. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:CABEB580-7591-4F49-A838-280C6DE0B0F9 .     

Evidence of a Cadmium-Thionein and the Glycine Cleavage System in Oxytricha granulifera

ABSTRACT. This work presents the further purification of a Cd-linking protein in Oxytricha granulifera by reverse-phase chromatography. This protein contains 25% cysteine and no aromatic amino acid. it may be considered as a chelatin with some similarity to metallothioneins. During the purification of another Cd-linking compound, we were able to demonstrate that the H protein precursor of glycine cleavage is present in Oxytricha. This is the first finding of the presence of this system in Protozoa.     

Sulphate Uptake in Two Mutants of Chlorella vulgaris with High and Low Sulphur Amino Acid Content

Two mutants of Chlorella vulgaris characterized by higher and lower content of sulphur amino acids compared with the wild strain were assayed for the efficiency of the sulphate uptake mechanism. In both mutants uptake exhibited positive cooperation kinetics and was strongly stimulated by sulphate starvation. Stimulation was depressed by cysteine and to a higher extent by methionine. Mutations affected the uptake efficiency concordantly with the level of sulphur amino acids. Addition to the starved strains of sulphate or chromate reduced the induced transport to the lower values of the non-starved strains. Addition of cycloheximide during the induction period prevented a further enhancement of transport without depressing the attained rate in the low sulphur mutant; it was followed by a rapid fall to the non-induced rate in the high sulphur mutant.     

Grain aphid clones vary in frost resistance,but this trait is not influenced by facultative endosymbionts

1. Facultative endosymbiotic bacteria of insects are known to affect life‐history traits of their hosts, and can provide important fitness benefits under certain environmental conditions. While several distinct endosymbiont‐induced effects have been reported, there is no data on whether heritable facultative endosymbionts in any species affect their hosts' performance at low temperatures, something that could have a major effect on insect physiology and survival, and thus population structure and distribution. 2. The original facultative endosymbionts were experimentally removed from five clonal genotypes of the grain aphid, Sitobion avenae Fab., which were then exposed to frost. 3. Aphid genotypes differed considerably in survival following the exposure and in fecundity of the survivors. However, the presence of the facultative symbionts had no overall effect on the studied traits. 4. The results suggest that the facultative symbionts have limited effects on the cold hardiness of their grain aphid hosts.